Fluorocarbon resin, particularly polytetrafluoroethylene (PTFE), has been used widely in various applications in the industrial filed and the consumer products because of its low friction properties, high thermal resistivity, excellent electrical properties, high chemical resistivity, and cleanness (anti-staining properties). However, certain cases have not permitted use of fluorocarbon resin because of its abrasion or creep deformation being large under sliding-use conditions or compression-bearing conditions at high temperatures. To deal with this problem, addition of some filler to fluorocarbon resin has been employed to improve its abrasion and creep deformation properties.
However, addition of filler increases friction resistivity and therefore tends to damage the member on the other side of a slide-member. Further, to add filler may invite pollution problem caused by the filler included in abrasion powder generated in sliding motion. JP 09-278907A and JP 11-116707A describe that it is effective in dealing with above stated problems to modify fluorocarbon resin by irradiating the resin with ionizing radiation in inert gas atmosphere with the resin heated over its melting point. The modification in this manner is a very effective method that is able to improve the abrasion resistivity or creep resistivity, or both, without changing the resin's inherent friction resistivity. However, the improvement in abrasion resistivity is not necessarily enough for a use under high pressure over 1 MPa; then, further improvements are desired.
The prior art which relates to the present invention is disclosed in the following documents.    {Patent Literature 1} JP 09-278907 A    {Patent Literature 2} JP 11-116707 A    {Patent Literature 3} JP 2009-13402 A